The field of the present invention relates to vibratory screening machines and conveyors using flexible mats.
Various designs have been proposed for sieve mat screening machines. For example, prior art screening machines have consisted of an elongated support frame with a mobile, deformable sieve mat, typically comprised of a plurality of sieve mat sections and having lateral edges extending in the direction of the length of the support frame in a series of alternating immobile and mobile sieve mat carriers mounted on the support frame and extending transversely along the length thereof, the sieve mat sections being affixed to the carriers with the mobile carriers being movable with respect to the support frame in the direction of the length of the support frame. During cycling of the screening machine, the individual screen mat sections are alternately tensioned and relaxed. The screening machine has a flat sieve mat with seals between the sieve mat and the adjacent side walls. Material being screened by the machine would engage these side seals causing additional wear. Attempts have been made to address this wear problem. For example, U.S. Pat. No. 5,062,949 discloses a screening machine having lateral sieve mat sides that are extended upwardly relative to the carriers and raised to form vertical side walls for the sieve mat, the carriers further including support shoulders for the lateral sides of the sieve mat, and the lateral sides being free of perforations in the vicinity of the shoulder.
The present inventors have recognized certain problems and limitations inherent in the prior sieve mat screening machines.